A golf course close to the Dounreay nuclear plant may be forced to close because of the discovery of tiny radioactive particles on the sea bed at a nearby beach.
Monthly monitoring of the beach, in Caithness on Scotland's north coast, has found about 16 particles since 1997.
The particles are about the same size and weight as grains of sand. Geoffrey Minter, who owns the 10,000-acre Sandsite estate, which includes both the Reay Golf Course and the beach, said the particles could easily be blown on to the course.
Health experts have warned that the most dangerous particles could kill or cause cancers if they are swallowed or inhaled.They could also cause blistering if they are handled.
The discovery of the particles, which were on the sea bed near the plant's outfall pipes, has already led to a fishing ban and marine exclusion zone.
Mr Minter has criticised the quality of the monitoring and wants an indemnity by the end of the month against any potential legal claims made against him.
If the UK Atomic Energy Authority (UKAEA), which runs Dounreay, refuses to take the responsibility for legal action, Mr Minter says he will close the golf course, which runs next to the beach.
He is also considering barring the monitoring staff – who check for levels of radioactivity using a vehicle-based Geiger counter – from his land unless the inspection teams are significantly increased.
Mr Minter dismissed claims by Dounreay officials that particles blown from the beach would be detected during the monitoring process.
"We have a duty of care to warn people," he said. "There is certainly a hazard."
Mr Minter, who took on the estate in 1991, has brought in researchers from Manchester University, headed by chemist Dr Philip Day, to look into the UKAEA studies.
Even though Dounreay officials have said that they were doing everything they could to trace the source of the particles, the researchers claim that less than 1 per cent of the radioactive grains on the beach have been found.
A spokesman for UKAEA said last night that the Scottish Environment Protection Agency oversaw their work. The spokesmen said: "They are satisfied with the monitoring that we have carried out."